"I'm fat," the 5'1" Fisher, 54, tells People, adding that she weighed 180 lbs. at her heaviest. "All the clothes in my closet belong to another chick. They have to make a new alphabet for my bra size."

Fisher -- who weighed around 105 lbs. during her Star Wars days in the late '70s and early '80s -- says her weight escalated over the past few years when she began touring her one-woman show Wishful Drinking.

She says she coped with the September death of her father, singer Eddie Fisher, by downing Häagen-Dazs ice cream bars. "That was bad," she says. "I was in denial."

Since joining Jenny Craig in late November, she has shed 12 lbs in 6 weeks thanks to plan-approved meals and exercising five days a week.